DNA Flashcards
What unzips DNA
DNA helicase
Structure of DNA
Sugar- deoxyribose
Phosphate
Nucleotide
What must be added before DNA polymerase and what does it do
RNA primase, starts adding complementary nucleotides
What does DNA polymerase do?
Add complementary nucleotides
What joins gaps on lagging strand?
DNA ligase
Central dogma
DNA-RNA-Protein
Steps of gene expression
Transcription
RNA processing
Translation
Where do the gene expression steps occur
Transcription, processing in nucleus
Translation in cytoplasm w/ help of ribosome
Steps of transcription
Initiation
Elongation
Termination
Describe initiation
Promoter bonds w/ RNA polymerase and it contains aug, the start codon. Transcription factors help promoter and RNAP bond. Euks have TATA box for initiation
Describe elongation
RNAP unwinds DNA 10-20 strands at a time
RNAP transcribes 40 bases per second
A gene can be transcribed by more than one RNAP at a time
RNAP adds nucleotides to 3’ end of RNA transcript
Describe termination
Proks have a terminator (opposite of promoter)
Euks have poly a signal to stop RNAP
RNA processing
Phosphate cap on 5’ end, poly a tail on 3’ to help export mRNA from nucleus and protect it from enzymes
Introns spliced out, exons together
Describe translation
tRNA transfers amino acids to a growing polypeptide chain at a ribosome
Requires:
Match between tRNA anticodon and amino acid
Match between tRNA anticodon and mRNA codon
tRNA
Shaped like t, has amino acid and anticodon on it
Ribosomes
Pair codons and anticodons, “hold up” polypeptide chain as it’s being made
rRNA is a component of ribosomes
Mutations
Missence- change letter- change codon- change aa
Nonsense- change letter- stop codon
Silent- change letter- same codon- same protein
What happens in a mutation
Substitution- switch pair
Insertion- add pair
Deletion- delete pair
Frameshift- switch reading frame
